Path: utzoo!utgpu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!ria!cs!wsaba From: wsaba@cscs.uwindsor.ca (Walid Saba) Newsgroups: comp.ai.philosophy Subject: Re: AGAINST FORMALISM? Summary: Existing Logical Systems are Only a Blueprint... Keywords: REASONING (is the keyword)! Message-ID: <557@schoenfinkel.cscs.uwindsor.ca> Date: 21 Jun 91 07:53:12 GMT References: <549@schoenfinkel.cscs.uwindsor.ca> <1991Jun20.201004.2277@arcturus.uucp> Organization: School of Computer Science, Univ. of Windsor, Ontario, Canada Lines: 76 In article <1991Jun20.201004.2277@arcturus.uucp>, berry@arcturus.uucp (Berry;Craig D.) writes: > > [deleted stuff...] > > I have a fundamental objection to refering to our cognitive processes as a > logical system of any type. A formal logical system must be reproducible - > e.g., if I conclude that "pregnant => female" given my current internal > state today, I should conclude the same thing given the same state at any > other time. My assertion is that the underlying uncertainties of brain > physiology negate this criterion. What I had for breakfast could skew > synaptic responses just enough to move around a few truth values, without > any new evidence or such being available. Every one who replied to the original article (AGAINST FORMALISM?), except Smoliar, is interpreting "logical reasoning" out of context. I tried to say that by "logical reasoning" I only mean some type of LOGICal reasoning. That is we don't know what LOGIC it is, it could be a logic that has much more powerful tools than logical syatems have at the moment... For example, consider the following: - he failed the test (1)... Dr. Frost told his student that - he is taking a sabbatical next year (2)... - he should be at his office in the morning (3)... In (1) he is a reference to the student, in (2) to Dr. Frost, and in (3) it could be to either one... This of course is based on contextual world knowledge. Yep!!! No need to understand synaptic responses to solve these types of problems. Formal logic can accomodate this context-dependent interpretation. So, we perhaps extend logical systems soem more... May be context must be ivestigated furthur. Context is very essential. And Logics can deal with contexts, although no formal account of context is yet available for the general contextual analysis (I am still looking forward to hear or read about McCarthy's efforts in this subject. He did say that his main concern is to formalize the notion of context...). After all this introduction, you are right, "pregnant => female" could be accepted at some "internal state" (which I will simply call state), and the same implication might not hold in a different state! EUREKA *** What did we discover? This is an old and already solved problem in logical semantics. Interpretation could be done with respect to states, possible worlds, etc. For example, there could be mythical world where "pregnant" implies "male" (!). Intensional, and modal logics are powerful enough to accomodate for this situation. I do not know much about the brain physiology, but I think the problem in network, *PDP*, biological, ... , models is that they are missing the point. WE ARE NOT INTERESTED IN THE HARDWARE (Brain) rather WE ARE INTERESTED IN SOFTWARE (Mind, this big program that runs the every action of an individual). The only problem that I see in formal, logical semantics are that they are at the moment not flexible enough to cope with contextual world knowledge. There is however progress in this regard. And whatever the case may be at the moment, we should never forget that No progress in any sientific inquiry can be made unless it is based on solid foundation. Logical systems allow us to make a giant leap, they allow abstraction, generalization, and they describe the right way of doing things... I must say I like what Minsky states every now and than. It has in effect the following meaning (sorry if the qoute is not accurate enough): logic is perhaps useful is describing certain things, but not in explaining how and why things happen in a certain way. But if logical syatems can (from the expressive power point of view) describe a certain phenomena, they can be used to make giant steps (extrapolate, generalize) to explain general rules. They can be used then to "deduce" how larger things are operating, etc. In nay case, I am still hoping that the logic of CHEO WAWA will do the job !!! WALID SABA wsaba@cs.uwindsor.ca Comp. Sci., Windsor, Ontario, Canada.